1. Field
The embodiments described below relate generally to the delivery of therapeutic radiation to a patient. More specifically, some embodiments are directed to treatment verification systems used in conjunction with such delivery.
2. Description
Conventional radiation treatment directs a radiation beam toward a tumor located within a patient. The radiation beam delivers a dose of therapeutic radiation to the tumor according to a pre-established treatment plan. The delivered radiation kills cells of the tumor by causing ionizations within the cells.
Radiation treatment plans are designed to maximize radiation delivered to a target while minimizing radiation delivered to healthy tissue. These goals might not be achieved if the radiation is not delivered exactly as required by the treatment plan. More specifically, errors in radiation delivery can result in low irradiation of tumors and high irradiation of sensitive healthy tissue.
Delivery errors may arise from many sources. For example, a patient position may vary from that designated by a treatment plan, and/or internal patient anatomy may be displaced with respect to external visible markers. Quality assurance procedures are typically performed in order to detect and correct potential radiation delivery errors. These procedures are particularly time-consuming and often inefficient, and are therefore only performed periodically prior to delivery of a treatment fraction.
Current trends point to hypofractionated delivery in which high doses are delivered per each treatment fraction. These trends increase the necessity of precise positioning during any given treatment. Delivery errors may also be identified after treatment, in which case a next fraction may be modified in an attempt to account for the errors. The latter approach is particularly troublesome, as unintentional delivery of radiation to sensitive tissues obviously cannot be undone.
In view of the foregoing, what is needed is a system to efficiently identify potential delivery errors so that treatment may be modified and/or suspended. It is further desirable to identify such errors prior to delivery of each beam of a treatment fraction.